Pressure regulatory assemblies are used to control the distribution of gas or fluids from pressure vessels storing the gas or fluids at a pressure that is different from ambient pressure. Pressure vessels are used in a variety of applications and industries, including but not limited to the storage of breathing oxygen. If a pressure vessel is fully discharged and a fluid connection (such as a leak path) remains from outside the vessel to inside the vessel, outside gases, liquids, and/or particulate containments may be introduced inside the vessel, which dilutes the purity of gas or fluids within the vessel. As such, after being fully depressurized, the pressure vessel must be purged and/or cleaned, which is costly and time consuming.